Very Young Planetary System: HR 8799

"Wild Solar System Spotted Around Distant Star"
Space.com (November 10, 2009)

"A young star observed by the Spitzer Space Telescope appears to be home to a wild – and young – planetary system that shares some of the frenetic dynamics thought to have shaped the early years of our own solar system.

"The Spitzer observations suggest young planets circling the star are disturbing smaller comet-like bodies, causing them to collide and kick up a huge halo of dust.

"The star, called HR 8799, became one of the first of two stars with planets that were directly imaged from Earth in November 2008. Ground-based telescopes at the W.M. Keck Observatory and the Gemini Observatory, both in Hawaii, took images of three planets orbiting in the far reaches of the system. Each of the three distant worlds is roughly 10 times the mass of Jupiter.

"HR 8799 is younger and more massive than our sun, which is more than 4.5 billion years old and more than 300,000 times the mass of Earth. It is about 129 light-years from Earth, so scientists weren't sure if Spitzer would be able to snap a picture of its debris disk. But to their amazement, it succeeded...."

Observations of HR 8799 are a pretty big deal, since the less-implausible models of how the Solar system developed say that there was an exciting period, early on, when the planets weren't in quite the same orbits they are now. Particularly Jupiter and Saturn - and that as those heavyweights moved around, they nudged things like comets and asteroids around.

Some of which hit Earth. Which is just as well, since it's quite possible that's how we got the water we're using now.

Back to HR8799 - it's a quite young system and, at a distance of 129 light-years, fairly close. And, it's the only star we know of, other than Fomalhaut, with a planetary system at this stage of development.

Exciting times.

Related posts, at

• "A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence"